Evidences of basal lactate production in the main white adipose tissue sites of rats. Effects of sex and a cafeteria diet

PLoS One. 2015 Mar 5;10(3):e0119572. doi: 10.1371/journal.pone.0119572. eCollection 2015.

Abstract

Female and male adult Wistar rats were fed standard chow or a simplified cafeteria diet for one month. Then, the rats were killed and the white adipose tissue (WAT) in four sites: perigonadal, retroperitoneal, mesenteric and subcutaneous (inguinal) were sampled and frozen. The complete WAT weight in each site was measured. Gene expression analysis of key lipid and glucose metabolism enzymes were analyzed, as well as tissue and plasma lactate and the activity of lactate dehydrogenase. Lactate gradients between WAT and plasma were estimated. The influence of sex and diet (and indirectly WAT mass) on lactate levels and their relationships with lactate dehydrogenase activity and gene expressions were also measured. A main conclusion is the high production of lactate by WAT, practically irrespective of site, diet or sex. Lactate production is a direct correlate of lactate dehydrogenase activity in the tissue. Furthermore, lactate dehydrogenase activity is again directly correlated with the expression of the genes Ldha and Ldhb for this enzyme. In sum, the ability to produce lactate by WAT is not directly dependent of WAT metabolic state. We postulate that, in WAT, a main function of the lactate dehydrogenase path may be that of converting excess available glucose to 3C fragments, as a way to limit tissue self-utilization as substrate, to help control glycaemia and/or providing short chain substrates for use as energy source elsewhere. More information must be gathered before a conclusive role of WAT in the control of glycaemia, and the full existence of a renewed glucose-lactate-fatty acid cycle is definitely established.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue, White / metabolism*
  • Animals
  • Female
  • Lactates / metabolism*
  • Male
  • Rats
  • Rats, Wistar
  • Sex Factors*

Substances

  • Lactates

Grants and funding

This study was done with the partial support of grants of the Plan Nacional de Investigación en Biomedicina (SAF2012-34895) and the Plan Nacional de Ciencia y Tecnología de los Alimentos (AGL-2011-23635) of the Government of Spain, as well as of CIBER-OBN (Institute of Health Carlos III). S. Agnelli was the recipient of a Leonardo da Vinci fellowship, and S. Arriarán a predoctoral fellowship of the Catalan Government, in both cases covering part of the time invested in this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.